Magnetic separator with dynamic baffle system

ABSTRACT

A dynamic baffle system for a magnetic separator includes a containment barrier secured to a frame and positioned between a rotary screen drum and a magnetic drum. The dynamic baffle system further includes a baffle configured to block an opening of the containment barrier. The baffle is movable between an open position in which media mixture is capable of flowing from the containment barrier to the magnetic drum and a closed position in which the media mixture is prohibited from flowing from the containment barrier to the magnetic drum and configured to evenly build up on the containment barrier. The dynamic baffle system further includes a sensor and a controller coupled to the sensor and the baffle to control the amount of media mixture flowing from the rotary screen drum to the magnetic drum.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional Application of U.S. application Ser.No. 13/754,273, filed Jan. 30, 2013, titled MAGNETIC SEPARATOR WITHDYNAMIC BAFFLE SYSTEM, now U.S. Pat. No. 9,442,251, which is herebyincorporated herein by reference in its entirety.

BACKGROUND OF THE DISCLOSURE

1. Field of the Disclosure

This disclosure relates generally to the field of media recovery systemsfor surface preparation equipment, such as shot blast equipment, andmore particularly to an improved magnetic separator to improve theefficiency of separation of abrasive media from molding sand andmetallic fines.

2. Discussion of Related Art

Media recovery systems are used to return media, such as shot, grit,sand, and the like, to surface preparation equipment, such as shot blastequipment. A typical recovery system may include a magnetic separatorthat operates intermittently, resulting in varying amounts of abrasivemedia flow to the magnetic separator. The inconsistent use of themagnetic separator has posed a problem in its operation. Specifically,the flow of media over a magnetic drum of the magnetic separator can beobserved to advance and retreat across a face of the magnetic drum,which can be 60 to 72 inches long. This inconsistent application ofmedia results in uneven burdening of the media on the drum, and lessefficient cleaning. Similarly, as the media is conveyed to a lowerchamber of the magnetic separator, the media mixture is not fullydistributed along a length of the separator. In some cases, theinability to evenly distribute the media can also lead to an unbalanceddistribution along the length of the magnetic separator. In some cases,this can also lead to unbalanced distribution of media mixture to a shotwheel by way of an abrasive hopper, which can be designed to depend onan evenly distributed loading of abrasive media along the full length ofthe separator.

SUMMARY OF THE DISCLOSURE

A dynamic baffle system is fitted to a magnetic separator between arotary screen chamber and a magnetic drum. The dynamic baffle systemserves to spread abrasive/sand media mixture across a full length of thedrum by closing off a flow of mixture when a full load of media mixtureis not sensed. This spreading of mixture is accomplished in part bypositioning a sensor at an exit end of the magnetic separator, with thesensor acting to close off the baffle when there is no media mixturepresent. An outer flighting of the rotary screen acts to push mediamixture toward the exit end as it piles up, and the dynamic bafflesystem acts to provide a full abrasive/sand media mixture or none atall, until enough mixture builds up to provide a full load.

The dynamic baffle system of embodiments of the present disclosureprovides an evenly distributed flow of abrasive/sand media mixture alonga full length of the magnetic drum of the magnetic separator to improvethe efficiency of separation of the abrasive/sand media from moldingsand and metallic fines. The dynamic baffle system provides a moreefficient cleaning of abrasive resulting in an increase in life of blastwheel components, and more importantly, an increased cleaning efficiencyof products within the shot blast equipment since the steel abrasivecleans products more efficiently than molding sand.

One aspect of the present disclosure is directed to a dynamic bafflesystem for a magnetic separator of the type including a frame, a rotaryscreen drum secured to the frame and configured to receive abrasive/sandmedia mixture, and a magnetic drum secured to the frame and positionedbelow the rotary screen drum. In one embodiment, the dynamic bafflesystem includes at least one containment barrier secured to the frameand positioned between the rotary screen drum and the magnetic drum. Theat least one containment barrier has an opening formed therein. Thedynamic baffle system further includes a baffle configured to block theopening of the at least one containment barrier. The baffle is movablebetween an open position in which media mixture is capable of flowingfrom the at least one containment barrier to the magnetic drum and aclosed position in which the media mixture is prohibited from flowingfrom the at least one containment barrier to the magnetic drum andconfigured to evenly build up on the at least one containment barrier.The dynamic baffle system further includes a sensor configured to detectthe presence of media within the at least one containment barrier and acontroller coupled to the sensor and the baffle to control the amount ofmedia mixture flowing from the rotary screen drum to the magnetic drumvia the at least one containment barrier.

Embodiments of the dynamic baffle system may be directed to configuringthe at least one containment barrier to include a first sloping wallpositioned on one side of the rotary screen drum and a second slopingwall positioned on an opposite side of the rotary screen drum. The atleast one containment barrier further may include a horizontal wallextending from one of the first sloping wall and the second slopingwall. The opening is defined between the horizontal wall and the otherof the first sloping wall and the second sloping wall. The dynamicbaffle system further may include a shaft configured to rotate thebaffle between its open and closed positions and a stop secured to theframe and configured to limit the motion of the baffle when moving toits open position. The dynamic baffle system may also be alternativelyconfigured to rotate to a free swinging open position. The dynamicbaffle system further may include a burden plate secured to the frameand positioned adjacent the opening and configured to guide mediamixture around the magnetic drum. In one embodiment, the sensor is acapacitive proximity switch. The controller may be configured to controlthe movement of the baffle to the open position when the at least onecontainment barrier is completely full with media mixture, and tocontrol the movement of the baffle to the closed position when mediamixture contained within the at least one containment barrier retreatsfrom an exit end of the magnetic separator to enable an outer flightingof the rotary screen drum to push the media mixture to the exit end ofthe magnetic separator thereby resulting in a full distribution ofabrasive across a face of the magnetic drum. A timer may be coupled tothe controller to mitigate responses near a set point to avoidchattering of the baffle.

Another aspect of the present disclosure is directed to a magneticseparator includes a frame, a rotary screen drum secured to the frameand configured to receive abrasive/sand media mixture, a magnetic drumsecured to the frame and positioned below the rotary screen drum, and atleast one containment barrier secured to the frame and positionedbetween the rotary screen drum and the magnetic drum, the at least onecontainment barrier having an opening formed therein. In one embodiment,the dynamic baffle system includes a baffle configured to block theopening of the at least one containment barrier. The baffle is movablebetween an open position in which media mixture is capable of flowingfrom the at least one containment barrier to the magnetic drum and aclosed position in which the media mixture is prohibited from flowingfrom the at least one containment barrier to the magnetic drum andconfigured to evenly build up on the at least one containment barrier.The dynamic baffle system further includes a sensor configured to detectthe presence of media with the at least one containment barrier and acontroller coupled to the sensor and the baffle to control the amount ofmedia mixture flowing from the rotary screen drum to the magnetic drumvia the at least one containment barrier.

Another aspect of the disclosure is directed to a method of controllingthe flow of abrasive/sand media mixture within a magnetic separator. Inone embodiment, the method comprises: transferring media mixture from arotary screen drum to at least one containment barrier positioned belowthe rotary screen drum, the at least one containment barrier having anopening formed therein; sensing the presence of media mixture within theat least one containment barrier; and controlling the movement of abaffle between an open position in which media mixture is capable offlowing from the at least one containment barrier to the magnetic drumand a closed position in which the media mixture is prohibited fromflowing from the at least one containment barrier to the magnetic drumand configured to evenly build up on the at least one containmentbarrier.

One embodiment of the method includes controlling the movement of thebaffle to the open position when the at least one containment barrier iscompletely full with media mixture, and controlling the movement of thebaffle to the closed position when media mixture contained within the atleast one containment barrier retreats from an exit end of the magneticseparator to enable an outer flighting of the rotary screen drum to pushthe media mixture to the exit end of the magnetic separator therebyresulting in a full distribution of abrasive across a face of themagnetic drum.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In thedrawings, each identical or nearly identical component that isillustrated in various figures is represented by a like numeral. Forpurposes of clarity, not every component may be labeled in everydrawing. In the drawings:

FIG. 1 is a perspective view of a magnetic separator of an embodiment ofthe present disclosure;

FIG. 1A is a cross-sectional view of the magnetic separator shown inFIG. 1;

FIG. 2 is a front elevational view of the magnetic separator shown inFIG. 1;

FIG. 3 is a rear elevational view of the magnetic separator with outerpanels removed to reveal working components of the magnetic separatorincluding a dynamic baffle system;

FIG. 4 is a top plan view thereof;

FIG. 5 is a side elevational view thereof;

FIG. 6 is an enlarged detail view taken from FIG. 4;

FIG. 7 is an enlarged detail view of an arm stop of the dynamic bafflesystem;

FIG. 8 is an enlarged cross-sectional view of the dynamic baffle system;and

FIG. 9 is a schematic view of a control system of the magneticseparator.

DETAILED DESCRIPTION

For the purposes of illustration only, and not to limit the generality,the present disclosure will now be described in detail with reference tothe accompanying figures. This disclosure is not limited in itsapplication to the details of construction and the arrangement ofcomponents set forth in the following description or illustrated in thedrawings. The principles set forth in this disclosure are capable ofother embodiments and of being practiced or carried out in various ways.Also the phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” “having,” “containing,” “involving,” andvariations thereof herein, is meant to encompass the items listedthereafter and equivalents thereof as well as additional items.

Embodiments of the disclosure are directed to a magnetic separatorhaving a dynamic baffle assembly that includes a sensor to signal thepresence or absence of abrasive/sand media mixture at an exit end of themagnetic separator. The sensor indicates whether a full loading ofabrasive/sand mixture is present to form a uniform loading across a fulllength of a rotary magnetic drum of the magnetic separator. When a fullload is indicated, an actuator releases a swinging or rotary baffle toallow the baffle to act as a standard compensating baffle. When theabrasive/sand media mixture retreats from the exit end of the magneticseparator, the actuator pushes the baffle closed, thus allowing an outerflighting of the rotary screen to push the abrasive/sand media mixtureload to the exit end, resulting in a full distribution of abrasiveacross a face of the magnetic drum. During steady state operation, itmight be expected that the abrasive/sand media mixture would back awayfrom the end of the magnetic separator at approximately the sameinterval as an intermittent operation of the blast wheels. To this end,a timer is used within the system to mitigate responses near the setpoint to avoid chattering of the baffle.

A loading of the abrasive/sand media mixture is directed across the faceof the magnetic drum and kept in close proximity to the magnets by aburden plate that conforms to the shape of the magnetic drum. Theabrasive/sand media mixture is dropped out into a separator compartmentand the steel abrasive is conveyed into a hopper by way of a secondaryair wash cleaning and on to the blast wheel. The process of operation ofseparating magnetic materials from the abrasive/sand media mixturefollowing the dynamic baffle system is typical among standard magneticseparators.

The sensor may consist of capacitive proximity switches, a differentialair pressure sensor, or a vibrating type sensor. All of these sensingelements serve to sense the presence or absence of abrasive/sand mediamixture, and trigger opening or closing of the dynamic baffle system.

Referring now to the drawings, a portion of a magnetic separator isgenerally indicated at 10. As shown, the magnetic separator 10 includesa frame 12 (FIG. 2) fabricated from structural steel or the like tosupport the working components of the magnetic separator. The magneticseparator 10 further includes a rotary screen drum 14 that is secured tothe frame 12 and configured to receive and deliver abrasive/sand mediamixture, hereinafter referred to as “media mixture.” As used herein,media mixture shall include any abrasive material, such as steel shotused in surface preparation, including shot blast, equipment. The rotaryscreen drum 14 includes a large diameter central portion 16 and reduceddiameter end portions, which are received within rotary bearings securedto the frame 12. A suitable drive mechanism, including a motor, isprovided to drive the rotation of the rotary screen drum 14. The centralportion 16 of the rotary screen drum 14 includes a flighting 22 that isconfigured to separate and evenly distribute media mixture that is fedto the rotary screen drum across a width of the rotary screen drum. Theflighting 22 serves as a rotary screw to move media mixture from one endof the rotary screen drum 14 to the other end of the rotary screen drum.In one embodiment, the drive mechanism may be located at an end of ascrew conveyor trough, which is positioned on an entrance end of themagnetic separator. Positioned below the rotary screen drum 14 is amagnetic drum 24 that is secured to the frame 12 and configured toattract magnet material within the media mixture. As with the rotaryscreen drum 14, the magnetic drum 24 includes a large diameter centralportion 26 and reduced diameter end portions, which are received withina rotary bearing on the drive end 28 (FIGS. 2-5) and a rigid mount onthe tail end, secured to the frame 12. A drive mechanism 30 is providedto drive the rotation of the magnetic drum 24.

In one embodiment, the platform of the magnetic separator 10 describedthus far may be a low-profile separator offered by WHEELABRATOR®, whichfeatures a magnetic separation system incorporated into an air-washseparator. The magnetic separator 10 is designed to magneticallyseparate abrasive media (either steel shot or grit) from sand or ferrousfrom non-ferrous media material by the rotating magnetic drum 24followed by the removal of fine waste material by an air-wash system.Magnetic separators, such as magnetic separator 10, may be used inselect applications for the automotive, aerospace, construction,foundry, pipeline and petroleum industries. The magnetic separator 10 isconfigured to remove sand from the steel shot even under extremely heavysand loads. The magnetic separator 10 increases the overall wear life ofcertain blast equipment component parts. This is because abrasive/sandmedia mixture significantly increases the wear on blast equipmentcomponent parts. Sand and abrasive (metallic) discharges from theelevator of a blast machine into an upper screw, which feeds the mediamixture to the rotary screen drum 14 of the magnetic separator 10 wheretrash and other oversized particles are removed. The media mixturepasses through the rotary screen drum 14 where it is metered onto thetop of the magnetic drum 24. The ferrous media mixture is held againstthe magnetic drum 24 to be released at a proper location while thenon-ferrous media mixture is allowed to flow directly into a dischargehopper to a disposable container or transporter for reuse. The releasedferrous abrasive mixture is directed to the air-wash system for removalof fines and reuse of the clean abrasive. This process is illustrated inFIG. 1A, which shows waste material W being separated from abrasive/sandmedia mixture A.

Access to the interior of magnetic separator 10 may be provided througha removable access cover 32 (FIG. 2) provided on a front of the magneticseparator. As shown, the access cover 32 includes a pair of handles,each indicated at 34, to enable an operator to remove the access cover.The access cover 32 further includes a mounting bracket 36, the purposeof which will be described as the description of the disclosureproceeds.

Referring now to FIGS. 2-9, a dynamic baffle system, generally indicatedat 40, of the present disclosure is shown and described as follows. Thedynamic baffle system 40 includes a containment barrier structuregenerally indicated at 42 that is secured to the frame 12 of themagnetic separator 10. As shown, the containment barrier structure 42 ispositioned between the rotary screen drum 14 and the magnetic drum 24 tocapture media mixture deposited from the rotary screen drum. Thecontainment barrier structure 42 includes a first sloping wall 44positioned on one side of the rotary screen drum 14 and a second slopingwall 46 positioned on an opposite side of the rotary screen drum. Thecontainment barrier structure 42 further includes a horizontal wall 48that extends from the first sloping wall 44. The component parts of thecontainment barrier structure 42, including the first sloping wall 44,the second sloping wall 46, and the horizontal wall 48, are each securedto the frame of the magnetic separator in a suitable manner. In oneembodiment, the containment barrier structure 42 may be fabricated fromsheet metal material.

As best shown in FIG. 8, a space or opening 50 between an edge of thesecond sloping wall 46 and an edge of the horizontal wall 48 defines anopening through which abrasive/sand media material exits from the rotaryscreen drum 14 to the magnetic drum 24. To contain and release materialwithin the containment barrier structure 42, the dynamic baffle system40 includes a baffle system, generally indicated at 52, which isconfigured to selectively block the opening 50 of the containmentbarrier structure. The baffle system 52, or simply baffle, includes abaffle plate 54, which may be fabricated from metallic material formedas a right-angle, and a shaft 56 secured to the baffle plate and thenrotatably secured to the frame 12 of the magnetic separator 10.Specifically, the baffle plate 54 is configured to move between an openposition in which media mixture is capable of flowing from thecontainment barrier structure 42 to the magnetic drum 24, and a closedposition in which the baffle plate engages the edge of the horizontalwall 48 and the media mixture is prohibited from flowing from thecontainment barrier structure to the magnetic drum. When closed, themedia mixture piles up within the containment barrier structure 42 withthe flighting 22 of the rotary screen drum 14 distributing media mixtureevenly within the containment barrier structure 42.

In one embodiment, the shaft 56 is configured to rotate the baffle plate54 between the open and closed positions by a motor 58, which may be thesame motor used to rotate the rotary screen drum 14 and the magneticdrum 24. Specifically, and with reference to FIGS. 2-4, the shaftextends through a bearing adaptor plate 74 provided in the frame 12 ateach end of the shaft (FIG. 4). Each bearing adaptor plate 74 isconnected to a drive arm 76, which in turn is connected to a cylinder78. When operating the motor 58, the cylinder 78 and the drive arm 76rotate the shaft 56 to move the baffle plate 54. To limit the movementof the baffle plate 54 when opening the baffle 52, the dynamic bafflesystem 40 further includes a stop 60 secured to the frame 12 of themagnetic separator 10. As shown in FIG. 8, the stop 60 is configured tolimit the motion of the baffle plate 54 when moving to its openposition. In one embodiment, a pneumatic cylinder may be used to actuatethe dynamic baffle. The rotary motion of the baffle 52 may alternativelybe provided by a small hydraulic cylinder, a screw jack actuator, orsome other similar device.

In one embodiment, the dynamic baffle system 40 further includes asensor 62 configured to detect the presence of media within thecontainment barrier structure 42. As discussed above, media mixturedelivered to the containment barrier structure 42 builds up when thebaffle 52 is in the closed position. The sensor 62 is secured to theframe 12 (sometimes referred to as a casing) of the magnetic separator10 and capable of detecting the presence of media mixture within thecontainment barrier structure 42. In a certain embodiment, the sensor 62is a capacitive proximity switch. Other sensors may also be used andfall within the scope of the present disclosure provided the sensor iscapable of detecting the presence or buildup of media mixture within thecontainment barrier structure 42. Referring back to FIG. 2, the sensor62 is secured to the mounting bracket 36, which is provided on theaccess cover 32. The containment barrier structure 42 forms a bottom ofa rotary screen chamber.

When a sufficient amount of media mixture is deposited within thecontainment barrier structure 42, the dynamic baffle system 40 opens thebaffle 52 to enable material to enter over the magnetic drum 24. Toautomate this process, the magnetic separator includes a controller 64that is configured to control the operation of the magnetic separator10. The controller 64 is further coupled to the sensor 62 and the baffle52 to control the amount of media mixture flowing from the rotary screendrum 14 to the magnetic drum 24 through the containment barrierstructure 42. The controller 64 is configured to control the movement ofthe baffle 52 to the open position when the containment barrierstructure 42 is completely full with media mixture, and to control themovement of the baffle 52 to the closed position when media mixturecontained within the containment barrier structure retreats from an exitend of the magnetic separator 10 to enable the outer flighting 22 of therotary screen drum 14 to push the media mixture to the exit end of themagnetic separator 10 thereby resulting in a full distribution of mediamixture across a face of the magnetic drum 24. In another embodiment,the dynamic baffle system further includes a timer 66 coupled to thecontroller 64 to mitigate responses near a set point to avoid chatteringof the baffle 52. FIG. 9 is a schematic view of the magnetic separatorhaving the dynamic baffle system 40 operating under the control of thecontroller 64. The drives of the rotary screen drum 14 and the magneticdrum 24 are independent from each other and may be under the control ofcommon or separate controllers and sensors.

In another embodiment, the magnetic separator 10 includes a burden plate68 secured to the frame 12 and positioned adjacent the opening 50 andconfigured to guide media mixture around the magnetic drum 24. As shown,the burden plate 68 is secured to the frame 12 of the magnetic separator10 by a bracket 70. The burden plate 68 is positioned closely to themagnetic drum 24 so that magnetic material engages the magnetic drumduring operation.

In certain embodiments, a sliding baffle plate 80 may be furtherprovided. The sliding baffle 80 is adjusted up or down to meter themedia mixture out of the bottom of the baffle 52 evenly. The slidingbaffle 80 assists in spreading the media mixture evenly by only allowinga certain amount of media mixture to flow out of the rotary screenchamber, thus acting as a dam that causes the abrasive to build upwithin the rotary screen chamber. This construction enables the outerband of the flighting 22 on the rotary screen to push the media mixturetoward the exit end of the magnetic separator. The sliding baffle 80ensures that the media mixture is delivered across the width of themagnetic separator thus preventing the media mixture from falling out atan entrance end, overloading the entrance end while leaving the exit endof the separator empty. The baffle system 52 of embodiments of thepresent disclosure evens out the media mixture when the media mixture ispresented to the separator in an intermittent loading. The slidingbaffle 80 is incapable of accommodating such intermittent loading.

A method of controlling the flow of abrasive/sand media mixture within amagnetic separator 10 comprises: transferring media mixture 72 (FIG. 8)from the rotary screen drum 14 to the containment barrier structure 42positioned below the rotary screen drum; sensing the presence of mediamixture within the containment barrier structure; and controlling themovement of the baffle 52 between the open position in which mediamixture is capable of flowing through the opening 50 from thecontainment barrier structure to the magnetic drum 24 and the closedposition in which the media mixture is prohibited from flowing from thecontainment barrier structure to the magnetic drum. In one embodiment,the step of controlling the movement of the baffle 52 further includescontrolling the movement of the baffle to the open position when thecontainment barrier structure 42 is completely full with media mixture72, and controlling the movement of the baffle to the closed positionwhen media mixture contained within the containment barrier structureretreats from an exit end of the magnetic separator 24 to enable anouter fighting 22 of the rotary screen drum 14 to push the media mixtureto the exit end of the magnetic separator 10 thereby resulting in a fulldistribution of abrasive across a face of the magnetic drum.

While most prior art devices principally consist of a scalping sectionprior to the magnetic separator that diverts abrasive loading above apreset level back to the bottom of an elevator, thus recycling theoverload through the elevator, the system of the present embodiment isrelatively simple, and can provide a gross adjustment to alleviateoverload conditions.

The main advantages of the dynamic baffle system described herein thismagnetic separation process include (1) increased effectiveness of ashot blast operation, (2) reduced blast cycle times, (3) increased lifeof replacement wear parts, (4) reduced equipment maintenance costs, and(5) reduced overall abrasive consumption.

Having thus described several aspects of at least one embodiment of thisdisclosure, it is to be appreciated various alterations, modifications,and improvements will readily occur to those skilled in the art. Suchalterations, modifications, and improvements are intended to be part ofthis disclosure, and are intended to be within the spirit and scope ofthe disclosure. Accordingly, the foregoing description and drawings areby way of example only.

What is claimed is:
 1. A method of controlling the flow of abrasive/sandmedia mixture within a magnetic separator, the method comprises:transferring the media mixture from a rotary screen drum to at least onecontainment barrier positioned below the rotary screen drum, the atleast one containment barrier having an opening formed therein; sensingthe presence of the media mixture within the at least one containmentbarrier, the sensing the presence of the media mixture being achieved bya sensor; and controlling the movement of a baffle between an openposition in which the media mixture is capable of flowing from the atleast one containment barrier to the magnetic drum and a closed positionin which the media mixture is prohibited from flowing from the at leastone containment barrier to the magnetic drum and configured to evenlybuild up on the at least one containment barrier, the controlling themovement of the baffle being achieved by a controller operativelycoupled to the baffle and the sensor.
 2. The method of claim 1, whereincontrolling the movement of the baffle further includes controlling themovement of the baffle to the open position when the at least onecontainment barrier is completely full with the media mixture, andcontrolling the movement of the baffle to the closed position when themedia mixture contained within the at least one containment barrierretreats from an exit end of the magnetic separator to enable an outerflighting of the rotary screen drum to push the media mixture to theexit end of the magnetic separator thereby resulting in a fulldistribution of abrasive across a face of the magnetic drum.